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Diagnosing CFRD — FAQs
Yearly Screenings — Taking the OGTT
The best way to diagnose CFRD is an oral glucose tolerance test (OGTT). This screening test is usually started at age 10 and done once a year when your health is stable (you are not sick).
The OGTT is done in the morning. You’ll fast (no food or beverages, except water) for at least 8 hours beforehand. You should eat your usual diet for 3 days before the test.
You will be given a sweet beverage to drink containing a high carbohydrate load (high glucose; a lot of sugar) dissolved in water. Then you’ll sit or lie quietly for 2 hours. Your blood sugar will be measured before you drink the beverage and again 2 hours later.
Your CF team will make a diagnosis of CFRD when:
Other Times to Screen — When You’re Sick or Pregnant
Besides the yearly screening, CFRD can also be diagnosed if you become sick, are on IV antibiotics and/or are taking steroids, or are pregnant.
Screenings When You Are Sick
When you are sick and in the hospital, your blood glucose is often checked for the first 48 hours after admission. It will be checked when you are fasting (before you eat) and 2 hours after you eat.
If you are sick and being treated at home, you should talk with your CF team members about checking your blood glucose with a blood glucose meter as instructed by your health care team. A diabetes diagnosis would have to be confirmed by a lab test at the hospital.
Screenings Related to Pregnancy
If you are planning on becoming pregnant, your CF team or your obstretrician may recommend an OGTT to rule out diabetes before getting pregnant.
If you should become pregnant and haven’t had an OGTT within the last 6 months, you should have an OGTT early in your pregnancy. If it is negative for diabetes, you should have another OGTT at 12 to 16 weeks and again at 24 to 28 weeks.
After delivery, you should have your blood glucose checked again within 6 to 12 weeks with an OGTT. Your obstetrician may be the one who orders these screening tests. If so, have the results — whether they are normal or abnormal — sent to your CF care team.Other Times to Screen for CFRD
High blood glucose can also occur with the use of high-calorie tube feedings. It is recommended that people getting tube feedings have their blood glucose checked every so often either at home with a glucose meter, or while in the hospital during the tube feeding to screen for CFRD.
People without CFRD who are listed for a lung transplant and have not been screened for CFRD within the last 6 months should be screened.
Blood glucose should be monitored after transplant while in the hospital. After being discharged, people who have had a transplant should have regular screening every year for CFRD if they have no symptoms.
Learn more about CFRD by watching the Cystic Fibrosis-Related Diabetes webcast series.